If you are on Ubuntu 12.04 I had the same problem and followed the instructions here:
The issue is they only have packages for Quantal and not Precise so this fix works as well while still getting updates.
Replace precise with your version of ubuntu.:
sudo add-apt-repository ppa:ui-toolkit/ppa sudo sed -i 's/precise/quantal/g' /etc/apt/sources.list.d/ui-toolkit-ppa-precise.list sudo apt-get update && sudo apt-get install qt-components-ubuntu qt-components-ubuntu-demos qt-components-ubuntu-examples qt-components-ubuntu-doc notepad-qml
Basically you can download the packages directly meant for 12.10 and use them on 12.04